The purpose of this project is to evaluate the role of environmental stimuli in the elicitation and maintenance of agitated behaviors in Alzheimer's disease patients. It is expected that an improved understanding of the interaction between agitated behaviors and environmental stimuli will lead to more effective treatment and prevention efforts. The first phase of the project involves three studies that are designed to further develop and validate a treatment-oriented taxonomy for classifying agitated behaviors in Alzheimer's disease patients, the Agitation Observation Checklist (AOC). The AOC system is based on the identification of environmental variables associated with the occurrence of agitation. It will provide clinically useful descriptive and prescriptive information by allowing caregivers and researchers to efficiently identify environmental variables that may be controlling agitated behaviors. Interjudge agreement and test-retest correlations of nurses' ratings will be computed in order to evaluate the reliability of the system. Concurrent validity will be evaluated through comparison of AOC identified situations and those observed in the natural environment. The predictive validity of the system will be evaluated through the assessment of response to intervention. The validity of the AOC for describing the relationship between agitated behavior and the environment will be evaluated within the context of two contemporary reinforcement theories, matching theory and behavioral regulation theory. The validity of these theories for describing the behavior of Alzheimer's disease patients and for predicting agitation and environment interactions will have implications for intervention and prevention efforts. Finally, because of the degenerative nature of Alzheimer's disease, progressive changes in the interaction of agitated behaviors and environmental stimuli will be evaluated over the course of the disease through a sequential developmental study of Alzheimer's disease patients at varying stages of the disease. Evaluation of changes in behavior-environment interactions is essential for elucidating factors associated with the maintenance of behavioral functioning, for enhancing the maintenance of intervention effects, and in the design of therapeutic environments that minimize the development of behavior problems.